Peter Ferrie on Microspft MMPC blog published a post explaining the term Virtual Machine; "When people in the industry talk about intentional obfuscation using vms, (note that these're not Virtual PC or VMware, but rather a technical term that was in use long before these products came into existence), the two examples that're most likely to come to mind are VMProtect and Themida -- which've been around since about 2004.
We can also find early examples of VMs in some adventure games from companies such as Infocom late 1970s, and Magnetic Scrolls early 1980s, which had copy-protection built into the code that ran in VMs. He cited an example of the 1983 game titled "The Last Gladiator" from Electronic Arts —
"it contained a vm devoted to implementing copy protection, and that supported only 18 instructions. The p-code hooked reset vector, and copied and decrypted next layer which was another vm. Second vm supported only 13 instructions, and contained a funny twist: most of tokens were same between the two vms, but in particular, branch instructions were reversed. That meant that a parser or emulator that understood the code of the first vm," explained Peter.
More Info: Prehistoric Virtual Machines